1. Field of the Invention
The invention relates to a process cartridge for use in an electrophotographic image forming apparatus such as a copying machine or a printer adopting an electrophotographic process, and holding means, cover means and charging moving means for acting on a process cartridge main body.
The electrophotographic image forming apparatus is an apparatus for forming an image on a recording material by the use of the electrophotographic process. Examples of the electrophotographic image forming apparatus include, for example, an electrophotographic copying machine, an electrophotographic printer (e.g. a laser beam printer, an LED printer or the like), a facsimile apparatus and a word processor or the like.
Also, the process cartridge refers to charging means, developing means, cleaning means and an electrophotographic photosensitive member integrally made into a cartridge which is made detachably mountable with respect to an electrophotographic image forming apparatus main body. Or it refers to at least one of charging means, developing means and cleaning means and an electrophotographic photosensitive drum integrally made into a cartridge which is made detachably mountable with respect to an electrophotographic image forming apparatus main body. Or it refers to at least developing means and an electrophotographic photosensitive drum integrally made into a cartridge which is made detachably mountable with respect to an electrophotographic image forming apparatus main body.
2. Description of the Related Art
An image forming apparatus such as a copying machine, a laser printer or a facsimile apparatus is such that selective exposure is effected on a photosensitive drum (image bearing member) uniformly charged by a charging apparatus to thereby form an electrostatic latent image, and this electrostatic latent image is developed as a toner image by a developing apparatus with a toner caused to adhere thereto, whereafter this toner image is transferred to a recording material such as paper to thereby form an image. Then, the image bearing member after the transfer of the toner image has any toner residual on its surface removed by a cleaning apparatus, and is used for the next image forming operation.
In recent years, there are known a photosensitive drum, a charging apparatus, a developing apparatus, a cleaning apparatus, etc., made into a cartridge by being integrally incorporated as a process cartridge. This process cartridge is designed to be detachably mountable with respect to an image forming apparatus main body and therefore, a user can mount the cartridge with respect to the image forming apparatus main body, whereby the user himself can simply perform the supply of a toner and the interchange of the photosensitive drum, thus achieving the facilitation of maintenance.
Further, in recent years, there has also been devised an image forming apparatus in which a developing operation is performed with respective independent developing devices for yellow, magenta, cyan and black selectively disposed relative to a photosensitive drum, or respective developing devices are fixedly disposed relative to a photosensitive drum and are selectively driven to thereby form a multi-color image, and a process cartridge for use in such multi-color image forming apparatus has also been put into practical use.
Here, as a charging apparatus in the above-described process cartridge, a non-contact type using corona discharge or the like and a contact type using a charging roller or the like are popular, but in recent years, the latter contact type has come to be generally used with a view to preventing the generation of ozone.
However, the charging apparatus of the above-described contact type, if left in contact with the photosensitive drum for a long period, has in some cases become such that a portion of a charging member (e.g., a charging roller) which contacts with the photosensitive drum causes permanent deformation, thus resulting in a change in its charging capability, and causing a faulty image having, for example, uneven density. Also, on the surface of the photosensitive drum, the photosensitive drum and the charging member frictionally contact each other due to vibration or the like during the transportation of the process cartridge, and a hysteresis remains as a charging memory, and this has sometimes led to the occurrence of a faulty image having, for example, uneven density. Consequently, when image forming is not effected, it is preferable to mitigate the contact pressure between the charging member and the photosensitive drum. For a similar reason, when image forming is not effected, it is preferable that a developer carrying member and the photosensitive drum which contact each other when image forming is effected be separated from each other.
As means for solving the above-noted problem, there have heretofore been disclosed a method of sandwiching a spacer member in an area (non-image forming area) between the surface of a photosensitive drum and a charging member and particularly outside an area (image forming area) into which an image is written, and holding it in a state in which the two are spaced apart from each other in an unused state (particularly during conveyance) (see, for example, Japanese Patent Application Laid-Open No. H02-39169), and a method of effecting pressurization and spacing apart by the use of a solenoid (see, for example, Japanese Patent Application Laid-Open No. H06-316349). Further, a construction in which one end of a toner seal is connected to this spacer member to thereby effect the opening of the toner seal and the detachment of the spacer at a time and decrease the user's work, thereby lightening a burden (see, for example, Japanese Patent Application Laid-Open No. 2001-201914) has been disclosed. However, in the method of sandwiching the spacer member between the photosensitive drum and the charging member, the photosensitive drum, the charging member and the spacer member frictionally contact with one another even in the non-image forming area and the surface states thereof are changed, and the contacting property between the two is changed. Also, when spacing apart is to be effected by the use of a solenoid, it is necessary to newly provide a complicated circuit. Also, to effect the opening of the toner seal and the detachment of the spacer at a time, a strong force has been necessary.
Also, when an attempt is made to space not only the charging member and the photosensitive drum, but also a developer carrying member and the photosensitive drum apart from each other, there have been the problems that the number of parts becomes great and the cost becomes high and that usability becomes poor.
On the other hand, recently, a process cartridge containing a storing element therein has made an advent. There is adopted a method of exchanging information regarding the quality of image, information regarding the manufacture and life of the process cartridge, information regarding the working state of an image forming apparatus main body, etc. between the storing element and the main body to thereby facilitate the maintenance of the image forming apparatus or the process cartridge, and improve usability (for example, U.S. Patent Application Publication No. US-2002-025185-A). The storage element effects communication with the image forming apparatus and therefore, a storing element main body and an electrical contact portion which is an example of the communication means thereof are usually installed on the outermost surface of the process cartridge.
During distribution or the like, however, there may occur pressure or frictional contact exceeding a condition supposed for the storing medium. In such a case, in the distribution process or the like, it is desirable to provide a member for protecting the storing medium besides the aforedescribed spacer member, but on the other hand, there is also conceived the occurrence of a reduction in usability by an increase in the number of parts and the user's work of detaching the member, and various inconveniences resulting from forgetting to detach the member.